1. Field of the Disclosure
The present disclosure relates to a transmission system and a transmission method which apply error correction coding to a digital signal from a client and decentralizes and sends the digital signal in a transmission interval constituted of a plurality of routes to collect again output signal from the transmission interval, and, thus, to perform error correction decode.
2. Discussion of the Background Art
In a present backbone such as a photonic network or a metro network, in order to enhance proof stress against a failure of an interface of a transmission device and a failure due to, for example, cutting of an optical fiber or to enhance reliability, there are undertaken efforts, such as transmitting the same signal to a plurality of routes or interfaces and build a system in the event of a failure of one of the interface and the optical fiber so that an actual transfer service is not affected.
In the conventional art, as such a protection technology, a 1+1 method, a 1:1 method, an N:1 method and so on are actually used. For example, in the 1+1 method shown in FIG. 1, a copy of a digital signal to be transmitted is created, and the copy is constantly transmitted simultaneously with the transmission of the original signal, using a transmission route of the original signal, a route different from an interface through which the signal passes, or an interface. In this technology, even if there occurs such an accident that a certain interface is failed, or a fiber in a certain interval is cut, by the use of a signal from a path or an interface which is not failed, the transmission of the digital signal is continued between a transmitting end and a receiving end without being stopped. In clients requiring high reliability, such a technology has been used.
Meanwhile, in the field of optical transmission technology, as described in the International Standard ITU-T G. 709, by the use of an error correction code, there has been realized a transmission method having high proof stress against, for example, a random error occurring in a transmission route interval. Consequently, enhancement of reliability and extension of the distance of the transmission interval are realized.